AB0744 “REACTIVE” MYOSITIS FOLLOWING ANTI-SARS-2 VACCINATION IN TWO PATIENTS CARRYING HLA-B*35 HAPLOTYPE
Authors: L. Punzi, D. Astorri, G. Carretta, C. Bernardi, A. Viola
Journal: Annals of the Rheumatic Diseases (2022)

Background The anti-SARS2 vaccination is considered the best way to reduce the frequency and the subsequent effects of COVID19 pandemic. To this aim, the most used in western countries are mRNA vaccines BNT16162b2 (Pfizer-BioNT) and mRNA-1273 (Moderna). With both these vaccines the risk/benefits balance is largely favorable and severe adverse effects are almost rare. In keeping, although transient myalgia and arthralgia are frequently seen, myositis have been until now rarely reported. Objectives To report two cases of myositis occurring in two patients after BNT16162b2 vaccine administration evaluated at the Center for Rheumatic Diseases in Venice, Italy. Methods In these patients clinical examination, blood and instrumental investigations for myositis and, in addition HLA typing, were performed. Patients were followed for at least six months after the onset of symptoms. Results The first patient, a 54-year-old male, complained of high-grade fever 4 days after the I dose of BNT16162b2 (Pfizer-BioNT) followed, by mild fatigue, muscle soreness and increasing weakness. He was sent to the emergency department of the local Hospital. The physical examination confirmed the muscle weakness. Blood investigation revealed an increase of AST: 509 U/L (NV&lt; 37), ALT:189 U/L (NV &lt;78), LDH 609, CPK 11394 U/L (NV&lt;, 309), Myoglobin 3571 ng/ml (VN &lt;96), CRP 1.6 mg/dl. Prednisone (PN) was started (50 mg orally day) and tapered to 5 mg in two weeks. At high doses, the symptoms slightly improved, but when &lt; 10 mg, all the symptoms reappeared. Thus, he was hospitalized again. The new examination confirmed the increase of all indices of myositis; antinuclear antibodies and myositis antibodies were absent and PN was restarted at 10 mg/day without benefit; echocardiography and TC scan were negative. He was then sent to our observation. We increased the dose of PN at 1 mg/PN/kg and we required HLA typing. Two weeks later symptoms disappared almost completely and then we tapered PN 5 mg/day weekly. At present the patients is completely well and muscle indices negative since two months. HLA typing revealed the presence of B*35 and DRB1*15. The second case was a 29-year-old female presented with a history of complaints appeared two days after the vaccination with BNT16162b2 administration (Pfizer-BioNT) characterized by three days of high-degree fever, followed by sever weakness, especially in the arms. The family doctor decide to hear our advise. At the initial presentation arm strenght was very decrease and the patient was accompanied. We required a serie of investigations which revealed: CPK 8950 U/L (NV 250), CRP 3.5 mg/dl increased; antinuclear and anti-myositis antibodies absent; cardiac (Ultrasound) and thoracic (CT) investigation and electromyography negative. HLA typing revealed the presence of haplotypes B*35 and DRB1*15. PN (50 mg orally day) was started; two weeks later she improved and both muscle indices and CRP negative. Thus, we reduce the dosage at 25 mg/day with tapering 5 mg weekly. She was completely remitted at end of PN cycle. At present, three month later she is well. Conclusion The rare occurrence of some particular side effects is not predictable. Our cases of severe myositis which in both cases completely remitted in some months are associated with haplotypes HLA-B*35 and DRB1*15. These are both binding sites linked to high-affinity interactions to S-protein T-cell epitope which account for high potentials to trigger immunogenic responses to the S protein of SARS-CoV-2 (1). Furthermore classically, HLA-B35 is associated with reactive arthritis and self-limiting, unclassified rheumatism (2). References [1]Sarma VR, Olotu FA, Soliman MERS. Integrative immunoinformatics paradigm for predicting potential B-cell and T-cell epitopes as viable candidates for subunit vaccine design againts COVID-19 virulance. Biomed J 2021; 44:447-60 [2]Dubost JJ, Demarquilly F, Soubrier M, Coussediere JM, Ristori JM, Sauvezie BJ. HLA and sel-limiting, unclassified rheumatism. A role for HLA-B35? J Rheumatol 1999; 26:2400-3 Disclosure of Interests None declared